Add graph for gate hit count

When looking at the gate failure rate it is easier to interpret it if
one knows how big the data set is.

Also change the color codes used to be brighter and human readable.
Color code names found here:
http://graphite.readthedocs.org/en/1.0/url-api.html

Change-Id: I7d304623b3c244876684ea2b0f822dee354b84c1
Merge "Add graph for gate hit count"